I have some how managed to lose all of my bookmarks. I am using Firefox 56.0.2, and sierra os. I have tried going to the Library folder, but under Application support there isn't a Firefox folder. My system hasn't crashed...What am I doing wrong and how do I get my bookmarks back?

If Firefox is run as a different user it won't have your bookmarks. To make sure this hasn't happened, start by rebooting the computer and try Firefox again. If that did not work, try the steps here: http://kb.mozillazine.org/Lost_bookmarks